[PATCH] UBI: block: Must use a mutex when using idr_alloc/idr_remove
Boris Brezillon
boris.brezillon at free-electrons.com
Wed Jan 17 12:10:18 PST 2018
On Wed, 17 Jan 2018 17:06:29 -0300
Ezequiel Garcia <ezequiel at vanguardiasur.com.ar> wrote:
> On 17 January 2018 at 17:04, Richard Weinberger <richard at nod.at> wrote:
> > Am Mittwoch, 17. Januar 2018, 20:46:51 CET schrieb Bradley Bolen:
> >> On 01/14/2018 05:20 PM, Ezequiel Garcia wrote:
> >> > On 14 January 2018 at 11:39, Boris Brezillon
> >> >
> >> > <boris.brezillon at free-electrons.com> wrote:
> >> >> +Ezequiel
> >> >>
> >> >> Hi Bradley,
> >> >>
> >> >> On Tue, 2 Jan 2018 21:26:09 -0500
> >> >>
> >> >> Bradley Bolen <bradleybolen at gmail.com> wrote:
> >> >>> This fixes a race condition where running ubiblock on multiple volumes
> >> >>> simultaneously produces the following splat.
> >> >>>
> >> >>> kernel BUG at kernel-source/fs/sysfs/group.c:113!
> >> >>> Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
> >> >>> [<c01e4160>] (internal_create_group) from [<c01e43fc>]
> >> >>> (sysfs_create_group+0x20/0x24)
> >> >>> [<c01e43fc>] (sysfs_create_group) from [<c00e4800>]
> >> >>> (blk_trace_init_sysfs+0x18/0x20)
> >> >>> [<c00e4800>] (blk_trace_init_sysfs) from [<c02bc734>]
> >> >>> (blk_register_queue+0x6c/0x154)
> >> >>> [<c02bc734>] (blk_register_queue) from [<c02cd610>]
> >> >>> (device_add_disk+0x2c8/0x450)
> >> >>> [<c02cd610>] (device_add_disk) from [<c0430fac>]
> >> >>> (ubiblock_create+0x254/0x2e4)
> >> >>> [<c0430fac>] (ubiblock_create) from [<c0421a3c>]
> >> >>> (vol_cdev_ioctl+0x3e0/0x564)
> >> >>> [<c0421a3c>] (vol_cdev_ioctl) from [<c018a55c>] (vfs_ioctl+0x30/0x44)
> >> >>> [<c018a55c>] (vfs_ioctl) from [<c018ad2c>] (do_vfs_ioctl+0x694/0x798)
> >> >>> [<c018ad2c>] (do_vfs_ioctl) from [<c018ae74>] (SyS_ioctl+0x44/0x6c)
> >> >>> [<c018ae74>] (SyS_ioctl) from [<c0010720>] (ret_fast_syscall+0x0/0x34)
> >> >
> >> > I'm a little confused, how does this stack trace relates to idr?
> >>
> >> I apologize. The commit message was a little terse. Here is the full
> >> output of the issue I ran into.
> >>
> >> ------------[ cut here ]------------
> >> block ubiblock0_3: created from ubi0:3(Partition3)
> >> block ubiblock0_2: created from ubi0:2(Partition2)
> >> block ubiblock0_4: created from ubi0:4(Partition4)
> >> WARNING: CPU: 1 PID: 179 at kernel-source/fs/sysfs/dir.c:31
> >> sysfs_warn_dup+0x68/0x88 sysfs: cannot create duplicate filename
> >> '/devices/virtual/bdi/252:2' Modules linked in:
> >> CPU: 1 PID: 179 Comm: ubiblock Tainted: P O
> >> 4.11.12-yocto-standard-414e5550071e0ca8639b0d8fb84fed31 #1 Hardware name:
> >> (Device Tree)
> >> [<c0019e50>] (unwind_backtrace) from [<c0014b20>] (show_stack+0x20/0x24)
> >> [<c0014b20>] (show_stack) from [<c02e2618>] (dump_stack+0x78/0x94)
> >> [<c02e2618>] (dump_stack) from [<c002ae6c>] (__warn+0xf0/0x110)
> >> [<c002ae6c>] (__warn) from [<c002aee0>] (warn_slowpath_fmt+0x54/0x74)
> >> [<c002aee0>] (warn_slowpath_fmt) from [<c01e2028>]
> >> (sysfs_warn_dup+0x68/0x88) [<c01e2028>] (sysfs_warn_dup) from [<c01e2120>]
> >> (sysfs_create_dir_ns+0x84/0x94) [<c01e2120>] (sysfs_create_dir_ns) from
> >> [<c02e44cc>] (kobject_add_internal+0x130/0x2f8) [<c02e44cc>]
> >> (kobject_add_internal) from [<c02e4730>] (kobject_add+0x9c/0xb8)
> >> [<c02e4730>] (kobject_add) from [<c03b2744>] (device_add+0xfc/0x56c)
> >> [<c03b2744>] (device_add) from [<c03b2d38>]
> >> (device_create_groups_vargs+0x90/0xd0) [<c03b2d38>]
> >> (device_create_groups_vargs) from [<c03b2dac>]
> >> (device_create_vargs+0x34/0x3c) [<c03b2dac>] (device_create_vargs) from
> >> [<c01301e4>] (bdi_register+0x70/0x1cc) [<c01301e4>] (bdi_register) from
> >> [<c01308f8>] (bdi_register_owner+0x3c/0x7c) [<c01308f8>]
> >> (bdi_register_owner) from [<c02cec04>] (device_add_disk+0x114/0x44c)
> >> [<c02cec04>] (device_add_disk) from [<c0436ec8>]
> >> (ubiblock_create+0x284/0x2e0) [<c0436ec8>] (ubiblock_create) from
> >> [<c0427bb8>] (vol_cdev_ioctl+0x450/0x554) [<c0427bb8>] (vol_cdev_ioctl)
> >> from [<c0189110>] (vfs_ioctl+0x30/0x44) [<c0189110>] (vfs_ioctl) from
> >> [<c01892e0>] (do_vfs_ioctl+0xa0/0x790) [<c01892e0>] (do_vfs_ioctl) from
> >> [<c0189a14>] (SyS_ioctl+0x44/0x68) [<c0189a14>] (SyS_ioctl) from
> >> [<c0010640>] (ret_fast_syscall+0x0/0x34) ---[ end trace e541910253daa337
> >> ]---
> >> ------------[ cut here ]------------
> >> WARNING: CPU: 1 PID: 179 at kernel-source/lib/kobject.c:240
> >> kobject_add_internal+0x1ec/0x2f8 kobject_add_internal failed for 252:2 with
> >> -EEXIST, don't try to register things with the same name in the same direc
> >> tory.
> >> Modules linked in:
> >> CPU: 1 PID: 179 Comm: ubiblock Tainted: P W O
> >> 4.11.12-yocto-standard-414e5550071e0ca8639b0d8fb84fed31 #1 Hardware name:
> >> (Device Tree)
> >> [<c0019e50>] (unwind_backtrace) from [<c0014b20>] (show_stack+0x20/0x24)
> >> [<c0014b20>] (show_stack) from [<c02e2618>] (dump_stack+0x78/0x94)
> >> [<c02e2618>] (dump_stack) from [<c002ae6c>] (__warn+0xf0/0x110)
> >> [<c002ae6c>] (__warn) from [<c002aee0>] (warn_slowpath_fmt+0x54/0x74)
> >> [<c002aee0>] (warn_slowpath_fmt) from [<c02e4588>]
> >> (kobject_add_internal+0x1ec/0x2f8) [<c02e4588>] (kobject_add_internal) from
> >> [<c02e4730>] (kobject_add+0x9c/0xb8) [<c02e4730>] (kobject_add) from
> >> [<c03b2744>] (device_add+0xfc/0x56c) [<c03b2744>] (device_add) from
> >> [<c03b2d38>] (device_create_groups_vargs+0x90/0xd0) [<c03b2d38>]
> >> (device_create_groups_vargs) from [<c03b2dac>]
> >> (device_create_vargs+0x34/0x3c) [<c03b2dac>] (device_create_vargs) from
> >> [<c01301e4>] (bdi_register+0x70/0x1cc) [<c01301e4>] (bdi_register) from
> >> [<c01308f8>] (bdi_register_owner+0x3c/0x7c) [<c01308f8>]
> >> (bdi_register_owner) from [<c02cec04>] (device_add_disk+0x114/0x44c)
> >> [<c02cec04>] (device_add_disk) from [<c0436ec8>]
> >> (ubiblock_create+0x284/0x2e0) [<c0436ec8>] (ubiblock_create) from
> >> [<c0427bb8>] (vol_cdev_ioctl+0x450/0x554) [<c0427bb8>] (vol_cdev_ioctl)
> >> from [<c0189110>] (vfs_ioctl+0x30/0x44) [<c0189110>] (vfs_ioctl) from
> >> [<c01892e0>] (do_vfs_ioctl+0xa0/0x790) [<c01892e0>] (do_vfs_ioctl) from
> >> [<c0189a14>] (SyS_ioctl+0x44/0x68) [<c0189a14>] (SyS_ioctl) from
> >> [<c0010640>] (ret_fast_syscall+0x0/0x34) ---[ end trace e541910253daa338
> >> ]---
> >> ------------[ cut here ]------------
> >> WARNING: CPU: 1 PID: 179 at kernel-source/fs/sysfs/dir.c:31
> >> sysfs_warn_dup+0x68/0x88 sysfs: cannot create duplicate filename
> >> '/dev/block/252:2'
> >> Modules linked in:
> >> CPU: 1 PID: 179 Comm: ubiblock Tainted: P W O
> >> 4.11.12-yocto-standard-414e5550071e0ca8639b0d8fb84fed31 #1 Hardware name:
> >> (Device Tree)
> >> [<c0019e50>] (unwind_backtrace) from [<c0014b20>] (show_stack+0x20/0x24)
> >> [<c0014b20>] (show_stack) from [<c02e2618>] (dump_stack+0x78/0x94)
> >> [<c02e2618>] (dump_stack) from [<c002ae6c>] (__warn+0xf0/0x110)
> >> [<c002ae6c>] (__warn) from [<c002aee0>] (warn_slowpath_fmt+0x54/0x74)
> >> [<c002aee0>] (warn_slowpath_fmt) from [<c01e2028>]
> >> (sysfs_warn_dup+0x68/0x88) [<c01e2028>] (sysfs_warn_dup) from [<c01e23c8>]
> >> (sysfs_do_create_link_sd+0xa0/0xbc) [<c01e23c8>] (sysfs_do_create_link_sd)
> >> from [<c01e2418>] (sysfs_create_link+0x34/0x44) [<c01e2418>]
> >> (sysfs_create_link) from [<c03b2a74>] (device_add+0x42c/0x56c) [<c03b2a74>]
> >> (device_add) from [<c02cec50>] (device_add_disk+0x160/0x44c) [<c02cec50>]
> >> (device_add_disk) from [<c0436ec8>] (ubiblock_create+0x284/0x2e0)
> >> [<c0436ec8>] (ubiblock_create) from [<c0427bb8>]
> >> (vol_cdev_ioctl+0x450/0x554) [<c0427bb8>] (vol_cdev_ioctl) from
> >> [<c0189110>] (vfs_ioctl+0x30/0x44) [<c0189110>] (vfs_ioctl) from
> >> [<c01892e0>] (do_vfs_ioctl+0xa0/0x790) [<c01892e0>] (do_vfs_ioctl) from
> >> [<c0189a14>] (SyS_ioctl+0x44/0x68) [<c0189a14>] (SyS_ioctl) from
> >> [<c0010640>] (ret_fast_syscall+0x0/0x34) ---[ end trace e541910253daa339
> >> ]---
> >> ubiblock (179): undefined instruction: pc=c01e26cc
> >> CPU: 1 PID: 179 Comm: ubiblock Tainted: P W O
> >> 4.11.12-yocto-standard-414e5550071e0ca8639b0d8fb84fed31 #1 Hardware name:
> >> (Device Tree)
> >> task: c185d780 task.stack: d053a000
> >> PC is at internal_create_group+0x3c/0x2a0
> >> LR is at sysfs_create_group+0x20/0x24
> >> pc : [<c01e26cc>] lr : [<c01e2950>] psr: 60000013
> >> sp : d053bd38 ip : d053bd70 fp : d053bd6c
> >> r10: c095fddc r9 : 00000000 r8 : c1b59c00
> >> r7 : c1b59870 r6 : c090f488 r5 : c09276f8 r4 : 00000000
> >> r3 : 00000000 r2 : c09276f8 r1 : 00000000 r0 : c1b59870
> >> Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
> >> Control: 30c5383d Table: 104b6840 DAC: ffab73de
> >> Code: e89da8f0 e1a0c00d e92ddff0 e24cb004 e24dd00c e52de004 e8bd4000
> >> e2507000 e1a09001 e1a05002 0a000004 e3510000 e59 74018 1a000002 e3540000
> >> 1a000002 (e7f001f2) e3540000 0a00000f e595300c e5951000 e3530000 1a00000d
> >> e5953010 e3530000 1 a00000a e59f2220 e3510000 e5973000 e59f0218 01a01002
> >> e59f2214
> >> ------------[ cut here ]------------
> >> kernel BUG at kernel-source/fs/sysfs/group.c:113!
> >> Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
> >> -----------[ user debug ]-----------
> >> Current process: ubiblock pid=179
> >> Running on CPU1 (2 online)
> >>
> >> current=c185d780 preempt_count=0x0
> >> CPU: 1 PID: 179 Comm: ubiblock Tainted: P W O
> >> 4.11.12-yocto-standard-414e5550071e0ca8639b0d8fb84fed31 #1 Hardware name:
> >> (Device Tree)
> >> task: c185d780 task.stack: d053a000
> >> PC is at 0x4b767d8c
> >> LR is at 0x10b78
> >> pc : [<4b767d8c>] lr : [<00010b78>] psr: 60000010
> >> sp : be73fc34 ip : 4b767d80 fp : 00000000
> >> r10: 00000003 r9 : be73fdb4 r8 : 00000000
> >> r7 : 00000036 r6 : 00000003 r5 : 000250a8 r4 : ffffffff
> >> r3 : 00000001 r2 : 22eea600 r1 : 40804f07 r0 : 00000003
> >> Flags: nZCv IRQs on FIQs on Mode USER_32 ISA ARM Segment user
> >> Control: 30c5383d Table: 104b6840 DAC: ffab73de
> >>
> >> Memory Maps:
> >> 00010-
> >> 00015
> >> ubiblock
> >>
> >> 00024-
> >> 00026
> >> ubiblock
> >>
> >> 00026-
> >> 00047
> >>
> >> 4b660-
> >> 4b67f
> >> ld-2
> >>
> >> 4b68e-
> >> 4b690
> >> ld-2
> >>
> >> 4b6a0-
> >> 4b7da
> >> libc-2
> >>
> >> 4b7da-
> >> 4b7dc
> >>
> >> b6bad-
> >> b6baf
> >>
> >> be71f-
> >> be740
> >>
> >> beb84-
> >> ---------[ end user debug ]---------
> >> Modules linked in:
> >> CPU: 1 PID: 179 Comm: ubiblock Tainted: P W O
> >> 4.11.12-yocto-standard-414e5550071e0ca8639b0d8fb84fed31 #1 Hardware name:
> >> (Device Tree)
> >> task: c185d780 task.stack: d053a000
> >> PC is at internal_create_group+0x3c/0x2a0
> >> LR is at sysfs_create_group+0x20/0x24
> >> pc : [<c01e26cc>] lr : [<c01e2950>] psr: 60000013
> >> sp : d053bd38 ip : d053bd70 fp : d053bd6c
> >> r10: c095fddc r9 : 00000000 r8 : c1b59c00
> >> r7 : c1b59870 r6 : c090f488 r5 : c09276f8 r4 : 00000000
> >> r3 : 00000000 r2 : c09276f8 r1 : 00000000 r0 : c1b59870
> >> Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
> >> Control: 30c5383d Table: 104b6840 DAC: ffab73de
> >> Process ubiblock (pid: 179, stack limit = 0xd053a210)
> >> Stack: (0xd053bd38 to 0xd053c000)
> >> bd20: d053bd5c
> >> d053bd48 bd40: c00731c8 d0bd9e00 c1b59800 c090f488 c1b59868 c1b59c00
> >> c1b5980c c095fddc bd60: d053bd7c d053bd70 c01e2950 c01e269c d053bd8c
> >> d053bd80 c00e3d38 c01e293c bd80: d053bdbc d053bd90 c02bdfbc c00e3d2c
> >> 00040b0c c1b59800 c1b59868 c090f488 bda0: c1b59870 c1b59c00 c1b5980c
> >> c095fddc d053be14 d053bdc0 c02cec84 c02bdef0 bdc0: c02ce6cc c1b59800
> >> d053bdfc d053bdd8 0fc00002 c0053478 00000000 1f518000 bde0: d053be1c
> >> 00040b0c 00000000 c1b11e40 00000000 c1b59800 c095fda4 d053be60 be00:
> >> c1b11e8c c095fddc d053be54 d053be18 c0436ec8 c02ceafc 00000000 c1b5980c
> >> be20: c01e06f0 c1b5980c 00000000 22eea600 d04b6100 d0b7cc00 d1c20000
> >> c090f488 be40: d053a000 c090f488 d053bedc d053be58 c0427bb8 c0436c50
> >> 00000001 00000000 be60: 00000000 0000000f 00000017 00000003 002c9000
> >> 00000000 00000001 00000003 be80: 00000000 00000000 00000001 0001f000
> >> 00000006 d0b7ce5c 0f700010 c005368c bea0: 9a877d41 00000007 c1aab015
> >> c0755170 00000261 00040b0c d053beec 22eea600 bec0: d0b96228 c1896300
> >> 00000003 22eea600 d053beec d053bee0 c0189110 c0427774 bee0: d053bf7c
> >> d053bef0 c01892e0 c01890ec d053bf34 c0185224 c01954e8 c05e9a14 bf00:
> >> c0185278 c1aab000 c090f488 c1896300 d0b96228 c1aab000 c1896308 00000020
> >> bf20: d053bf44 d053bf30 c0185224 c0163200 00000003 c090f488 d053bf94
> >> d053bf48 bf40: c0175504 c01851c4 00000000 00040b0c 00000002 00000003
> >> c1896300 c1896300 bf60: 40804f07 22eea600 d053a000 00000000 d053bfa4
> >> d053bf80 c0189a14 c018924c bf80: ffffffff 000250a8 00000003 00000036
> >> c00107e4 d053a000 00000000 d053bfa8 bfa0: c0010640 c01899dc ffffffff
> >> 000250a8 00000003 40804f07 22eea600 00000001 bfc0: ffffffff 000250a8
> >> 00000003 00000036 00000000 be73fdb4 00000003 00000000 bfe0: 4b767d80
> >> be73fc34 00010b78 4b767d8c 60000010 00000003 e675ff3a 2a3139dd [<c01e26cc>]
> >> (internal_create_group) from [<c01e2950>] (sysfs_create_group+0x20/0x24)
> >> [<c01e2950>] (sysfs_create_group) from [<c00e3d38>]
> >> (blk_trace_init_sysfs+0x18/0x20) [<c00e3d38>] (blk_trace_init_sysfs) from
> >> [<c02bdfbc>] (blk_register_queue+0xd8/0x154) [<c02bdfbc>]
> >> (blk_register_queue) from [<c02cec84>] (device_add_disk+0x194/0x44c)
> >> [<c02cec84>] (device_add_disk) from [<c0436ec8>]
> >> (ubiblock_create+0x284/0x2e0) [<c0436ec8>] (ubiblock_create) from
> >> [<c0427bb8>] (vol_cdev_ioctl+0x450/0x554) [<c0427bb8>] (vol_cdev_ioctl)
> >> from [<c0189110>] (vfs_ioctl+0x30/0x44) [<c0189110>] (vfs_ioctl) from
> >> [<c01892e0>] (do_vfs_ioctl+0xa0/0x790) [<c01892e0>] (do_vfs_ioctl) from
> >> [<c0189a14>] (SyS_ioctl+0x44/0x68) [<c0189a14>] (SyS_ioctl) from
> >> [<c0010640>] (ret_fast_syscall+0x0/0x34) Code: e89da8f0 e1a0c00d e92ddff0
> >> e24cb004 e24dd00c e52de004 e8bd4000 e2507000 e1a09001 e1a05002 0a000004
> >> e3510000 e59 74018 1a000002 e3540000 1a000002 (e7f001f2) e3540000 0a00000f
> >> e595300c e5951000 e3530000 1a00000d e5953010 e3530000 1 a00000a e59f2220
> >> e3510000 e5973000 e59f0218 01a01002 e59f2214
> >> ---[ end trace e541910253daa33a ]---
> >>
> >> I was able to reproduce the problem with the following script with the
> >> underlying volumes already created:
> >>
> >> while true; do
> >> for part in 2 3 4 15 24 90 91; do
> >> ubiblock -c /dev/ubi0_$part &
> >> done
> >> sleep 2
> >>
> >> for part in 2 3 4 15 24 90 91; do
> >> ubiblock -r /dev/ubi0_$part &
> >> done
> >> sleep 2
> >> done
> >>
> >> There is a race with idr_alloc where gd->first_minor could be set to the
> >> same value for two different calls to ubiblock_create. Each instance
> >> calls device_add_disk with the same first_minor. device_add_disk calls
> >> bdi_register_owner. The bdi_register_owner call path produces the
> >> initial WARNINGS about registering the same device. However,
> >> device_add_disk does not error out when bdi_register_owner returns an
> >> error. The control continues until it reaches blk_register_queue which
> >> eventually BUGs.
> >>
> >> >> Missing Fixes and Cc-stable tags.
> >> >>
> >> >>> Signed-off-by: Bradley Bolen <bradleybolen at gmail.com>
> >> >>
> >> >> Reviewed-by: Boris Brezillon <boris.brezillon at free-electrons.com>
> >> >>
> >> >> BTW, just had a quick look at the code, and I think the locking can be
> >> >> simplified a bit by keeping the devices_lock for the whole
> >> >> ubiblock_create() operation instead of acquiring/releasing it several
> >> >> times in the function (see [1]). It makes sense to do fine grained
> >> >> locking when operations protected by the lock are time sensitive, but I
> >> >> don't think this is the case here.
> >> >
> >> > Agreed. Something like this perhaps http://ix.io/E8G ?
> >> > Notice that ubiblock_remove_all seemed to require locking as well.
> >>
> >> I tried out Ezequiel's patch and it fixes this issue as well. Note,
> >> that ret needs to be defined in ubiblock_remove.
> >
> > Can you please have a proper patch such that I can take it? :-)
> >
>
> Bradley,
>
> Feel free to submit a patch based on the (untested) diff I sent.
> While there, you can improve the commit log with the details
> you sent.
Can we fix the locking in ubiblock_remove_all() as well?
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